大豆光合气体交换参数的QTL分析

光合气体交换参数是用来表示植物光合能力的常用指标。利用来自大豆品种科丰1号和南农1138-2的重组自交系群体NJRIKY(184个家系)及其分子遗传图谱，通过两年盆栽试验定位与光合速率、气孔导度、胞间CO₂浓度和蒸腾速率有关的QTL。结果表明，4个参数的遗传力中等偏低，在0.48~0.60之间；两两间存在极显著正相关关系，相关系数在0.192~0.686之间；两年共检测到15个QTL，分别位于C1、C2、D2、E、H、I和O连锁群上，LOD值在2.25~6.31之间，贡献率为4.80%~12.30%，；有6个QTL在不同环境下稳定表达，它们分别是控制光合速率的qPnC1.1、控制气孔导度的qSCD2.1和qSCI.1、控制胞间CO₂浓度的qCiI.1和qCiO.1，以及控制蒸腾速率的qTrO.1；检测到4个同时控制两个或两个以上参数的标记区间，它们分别是C1连锁群上控制光合速率和气孔导度的sat_311~sct_191区间，E连锁群上控制光合速率、气孔导度和胞间CO₂浓度的sat_172~satt268区间，I连锁群上控制气孔导度和胞间CO₂浓度的satt726~satt330区间，以及D2连锁群上控制气孔导度和胞间CO₂浓度的sat_296~sat_277区间。

QTL Mapping for Photosynthetic Gas-Exchange Parameters in Soybean

Photosynthesis plays an important role in determining crop’s yield. Photosynthetic gas-exchange parameters have been widely used to reflect the photosynthetic capacity of plant. The present study was conducted to identify QTLs associated with gas-exchange parameters in soybean. Pot experiments were carried out in two successive years to evaluate 184 recombinant inbred lines (RILs) derived from a cross between Kefeng 1 and Nannong 1138-2 for photosynthetic rate, stomatal conductance, intercellar CO₂ concentration and transpiration rate at R6 growth stage. The RILs showed transgressive segregation for these parameters, their broad heritability was lower-middle, ranging from 0.48 to 0.60, and significant correlations were observed among them. In total, fifteen QTLs located on seven linkage groups (LG) were identified, six of which expressed stably in two environments. The percentage of variation explained by these QTLs ranged from 4.80% to 12.30%, and with LOD scores from 2.25 to 6.31. Three QTLs for photosynthetic rate were placed on LG C1, E and O respectively, among which the QTL qPnC1.1 (flanked by markers sat_311 and sct_191) was detected in both years; four QTLs for stomatal conductance were placed on LG C1, D2, E and I, respectively, among which QTLs qSCD2.1 (flanked by sat_296 and sat_277) and qSCI.1 (flanked by satt726 and satt330) expressed stably in both years; five QTLs for intercellular CO₂ concentration were placed on LG C1, D2, E, I and O, respectively, among which QTLs qCiI.1 (flanked by satt726 and satt330) and qCiO.1 (flanked by satt94 and sat_291) were detected in both years; three QTLs for transpiration rate were placed on LG C2, H and O, respectively, among which QTL qTrO.1 (flanked by BE801128 and satt345) was detected in both years. It was found that in many cases some QTLs for different traits were located in the same regions of LG. A total of four genomic regions were detected controlling different parameters: the marker interval sat_311–sct_191 on LG C1 for photosynthetic rate and stomatal conductance simultaneously, with positive alleles from Nannong 1138-2; the marker interval sat_172–satt268 on LG E for photosynthetic rate, intercellular CO₂ concentration and stomatal conductance simultaneously, with positive alleles from Kefeng 1; the marker intervals sat_296–sat_277 on LG D2 and satt726–satt330 on LG I for stomatal conductance and interncellular CO₂ concentration simultaneously, with positive alleles from Nanong 1138-2 for the former marker interval, while from Kefeng 1 for the latter one. Compared with other studies, we did not find common QTL that could express stably across different genetic materials, which suggested that the genetic mechanism of photosynthetic gas-exchange parameters is complex in soybean, and further studies need to be performed with more soybean mapping populations in the future.